Extraction process



Patented Sept. 7, 1937' ax'raAc'noN raooass iil7illc1 ni.J. D. van Dijck, The Hague, Netherlands, asslgnor to Shell Development Gompany, San Francisco, Calif., a corporation of Delaware No Drawing. Application January Serial No. 1,028

6 Claims. (Cl. Nib-13) This invention relates to the separation of hydrocarbon mixtures into their component parts and is more particularly concerned with processes of manufacturing, by extraction, refined products from mineral oils, either crude or produced by distillation, cracking, hydrogenation, solvent extraction, or other processes.

In the recent development of the treatment of mineral oils by extraction processes, a large number of substances were discovered to possess the qualities of selective solvents, that is, of solvents which may be used to separate hydrocarbon mixtures into portions respectively more paraffinic and less paraffinic that the original oil.

It has now been found that a large group of nitrogen ring compounds, i. e. heterocyclic organic compounds having at least one nitrogen atom in the ring, possess to a high degree the properties of selective solvents suitable for treating hydrocarbon mixtures, and may be used according to this invention to improve such of their characteristics as color, viscosity index, Conraclson test, etc. This group comprises the following compounds: pyrrole, indole, pyrazole, pyrazoline, pyrazine, piperidine, quinoline, iso-quinoline, etc. and their carbon substituted derivatives formed by the substitution of one or more hydrogen atoms attached to carbon atoms in the ring by an active (polar) group, or radicle, such as alkyls, CN, N02, CO, OR SCN, COOR, Cl, 0, NHa, CS, where R designates either a hydrogen atom or an alkyl radiclef These carbon substituted derivatives of the basic'compounds may be illustrated, for example, by the following substances: alkyl pyrroles, such, for example, as 11- and/or 3- methyl-and/or ethyl pyrroles, chlor-pyrroles, nitro-pyrroles, cyano-pyrroles, amino-pyrroles, and pyrrylic acids, alkyl indoles, such as methyl and/ or ethyl indoles, chlor-indoles, nitro-indoles, cyano-indoles, amino-indoles, and indylic acids, alkyl pyrazoles, such as on and/or 5 methyl and/or ethyl pyrazoles. pyrazole cyanide, chlor-pyrazoles, nitro-pyrazolesf cyano-pyrazoles, aminopyrazoles, and pyrazolylic acids, alkyl pyrazolines, such as a and 5 methyl and/or ethyl pyrazolines, chlor-pyrazolines, nitro-pyrazolines, alkyl pyrazines, such as methyl and/or ethyl pyrazines, chlor-pyrazines, nitro-pyrazines, alkyl piperidine, such as and/or [3 and/or '1 methyl chlor-piperidines,

and/or ethyl piperidines, nitro-piperidines, alkyl quinolines, such as methyl and/or ethyl quinolines, chlor-quinolines, nitro-quinolines, alkyl iso-quinolines, such as 5 methyl and/or ethyl iso-quinolines, chlor-isoquinolines, and nitro-isoquinolines.

'plications Serial Nos. 455,

Further, the products of mixed, substitution of these products may also be used for this process, such, for example, as: cyano-hydroxy-pyrroles, nitro-hydroxy-pyrroles, chlor-hydroxy-pyrroles, chlor amino pyrroles, alkylamino pyrroles, cyano-hydroxy-indoles, nitro hydroxy indoles, chlor hydroxy indoles, chlor amino indoles, alkyl-amino-indoles, cyano-hydroxy-pyrazoles, nitro-hydroxy-pyrazoles, chlor hydroxy pyrazoles, chlor, amino-pyrazoles, alkyl-amino-pyrazoles, cyano-hydroxy-pyrazolines, nitro-hydroxypyrazolines, chlor-hydroxy-pyrazo1ines, chloramino-pyrazolines, alkyl-amino-pyrazolines, cyano-hydroxY-pyrazines, nitro hydroxy pyrazines, chlor-hydroxy-pyrazines, chlor-aminopyrazines, alkyl-amino-pyrazines, cyano-hydroxy-piperidines, nitro hydroxy piperidines, chlor-hydroxy-piperidines, chlor-amino-piperidines, alkyl-amino-piperidines, cyano-hydroxyquinolines, nitro-hydroxy-quinolines, chlor-hydroxy-quinolines, and chlor-amino-quinolines; cyano-hydroxy-isoquinolines, nitro-hydroxy-isoquinolines, ,chlor-hydroxy-isoquinolines and alkyl-amino-isoquinolines.

It must be noted that some of the nitrogenheterocyclic compounds, such, for example, as pyridine, are often unsatisfactory as extraction solvents by reason of their excessive miscibility with mineral oils at ordinary temperatures.

However, their derivatives of the class defined hereinbefore possess properties which make them highly suitable for the purposes of this invention. Thus alkyl pyridines, such as (1- and/or 5- and/or -methyl-pyridines (picolines), di-methyl-pyridines (lutidines) tri-methyl-pyridines (collidines), ethyl pyridines, propyl-pyridines, cyanopyridines, chlor pyridines, nitro pyridines, amino-pyridines, pyridylic acids, hydroxy-cyanopyridines, nitro-hydroXyyri'clines, droxy-pyridines, 'chlor-amino-pyridines, alkylamino-pyridines, etc., are all excellent solvents for separating mineral'oils into their components by extraction. It must be especially pointed out that the alkyl pyridines, such as the picolines, lutidines and collidines, mono-nitro-pyridines, such as 'y-nitro pyridine, form a class of extracchlor-hy- 40 tants particularly suitable for the purposes of this invention.

So far as the mechanism of the extraction process itself is concerned, it may be carried out in any conventional manner, including the processes of batch or continuous countercurrent extractions, and such as thosggdescribed in my ap- 9 filed May 26, 1930; 567,580 filed October 9, 1931; and 669,580 fll'ed May ti, The solvents of my invention may be used either alone or in solutions so called naphthenic solvents, such as iurfurai, chlorex, phenols, nitrobenzene, liquid S02, eta, and/or solvent diluents such as, benzol and other aromatic hydrocarbons to which they are added in sufiicient quantities to modify solvent characteristics. Often it may be desirable to dilute a viscous oil with a parafiiinic diluent, such as liquid propane or other parafimic solvent, and to extract the resultant solution.

The oil-solvent ratios may vary in difierent cases, depending, together with the temperature of extraction,.largely upon the characteristics of the hydrocarbon mixtures being treated and the properties of the desired product; it will be seen from the examples given below that-excellent results have been obtained by using 100% and 200% by volume of the solvent.

Example I.A raifinate obtained. by an SO2- benzol extraction of a distillate from Coalinga crude, having a Saybolt universal viscosity of 72 sec. at 210 F. and a viscosity index of 6 5, was extracted with 200% of a w-picoline, obtained as a derivative from ordinary commercial coaltar, having a specific gravity of .950 and boilling at about 129 C. The treatment yielded 50% of rafiinate having a Saybolt universal viscosity of 70.5 secs. at 210 F., a viscosity index of 9a, and a markedly improved color.

Example l'l.A ramnate obtained from a liquid S02 treatment oi a distillate of Coalinga crude and having a Saybolt universal viscosity of 52 sec. at 210 E, a viscosity index of 62, and an A. S. T. M. color of 3 /2, was extracted with 100% of quinoline at 32 25. The raifinate obtained has a Saybolt universal viscosity of 52.5 sec. at 210 F., a viscosity index of 79, and an A. S. T. M. color of 2+.

Example ZU.A Pennsylvanian lubricating oil with a viscosity index of 105 and an A. S. T. M. color of 7+ was extracted with 100% of quinoline, giving a raflinate with a viscosity index of 110 and an A. S. T. M. color oi 6+.

Example Iii-A mixed lubricating oil having a Saybolt universal viscosity of '70 sec. at 210' R, a viscosity index of 15 and an A. ST. M. color of Ii was extracted with of quinoline at 30 F. The rafiinate obtained had a Saybolt universal viscosity oi 64.5 sec. at 210 F., a viscosity index of 57 and an A. S. "2. Ni. color of i=/ Example V.--A lubricating oil obtained by an SOz-benzol treatment of a Coalinga distillate, and having a gravity of 255 A. P. L a Saybolt universal viscosity of 58.7 sec. at 210 lit, and a viscosity index of 69, was extracted with 100% of beta-gamma picoline at l0 F. The ratfinate obtained had a gravity of 26.5 A. P. I. a Saybolt universal viscosity of 57.9 sec. at 210 F., and a viscosityindex 01 72, and a greatly improved color.

The foregoing examples serve merely to illustrate the results of extracting hydrocarboxf oils with some of the new solvents, other solvents disclosed hereinbefore being also very efiective.

The extraction of oils with these new solvents may either precede or follow an extraction of the oil with other solvents. Thus, as described in the Examples I and II, an oil was first extracted with SOs-b61120]. solution in one case and with liquid SO: in the other case, and the resulting ramnat'es (the oil portions of the raflinate phases) were further refined by extraction with the solvents of this invention, Often it is des eaves sizable to extract with my solvents the refinate or extract p ases (oil plus a solvent) produced by refining with other solvents, without freeing the oil. from the solvent prior to such'an extraction. The advantage or such a method resides in the elimination of the step of separating the oil from the solvent between the two extraction steps, and also in the improved extraction efficiency resulting from the combined effect of the two solvents in the oil.

As an example, a hydrocarbon oil may he first extracted with liquid $02, or fur' m'al, or chlorex, or cresylic or phenol, or L o-benzene, or some other selective solvent, or s. xture of some of these solvents. In many cases the oil in the resulting rafiilnate phase, that is, in the solution of the solvent in the less soluble portion of the original 02, will have excellent characteristics in so far as the concentration of paraiiinic components, the viscosity index, etc., are concerned, but will fail, for example, to possess a sufficiently good color. In such cases it is of great advantage to extract this phase further with one of the solvents of this invention or their mixture whereby a raflinate phase consisting of a highly refined oil and a mixture of the two solvents is ob tained; the oil is then separated, e. g. by distih lation either with or without steam, from the solvents, and each solvent may be separated from the other. The extract phase, i. e. the solution of a less parafiinic portion of the oil being treated in the solvents used, is also treated to separate oil and the solvents. The recovered solvents may then be used again in the process.

On the other hand, it was often found very advantageous to extract the fractions of hydrocarbon oils containing asphaltic substances, first with the solvents of this invention, used in the amounts which may be relatively small but suincient to produce a positive effect in so far as the subsequent treatment with other solvents is ccs:-=

corned, and following this treatment of the oil by extracting the rafdnate or the rafiinate phase with such solvents as liquid $02 or furfural, or chlorex, or their equivalents mentioned hereinbefore. In the processes of this type the allrylateci and/or nitrated derivatives of pyridine, quinoline, isoquinoline, piperidine, pyrrole and indole, were found particularly suitable ior the first step of this process, whereby the asphaitic components of the oil are removed as extract without a great loss of the non-asphaltic components. The deasphaltized oil, i. e. either the rafrlnate phase or the raihnate separated at stage, is then refined by extraction with a diflerent selective solvent, such as liquid S02 or its equivalents, or some other nitrogen-containing heterocyclic compounds described hereinbeiore, the resulting ramnate and extract phases are separated from each other and each is treated further to separate 011 and the solvent used.

For any of the above described methods of ex-= tracting hydrocarbon oils, it may often be desirable, when employing the solvents of this invention to carry out the process in accordance with my invention disclosed in the application Serial No. 455,959, 1. e. to counterflow one of the solvents of the present invention and another solvent of the type of liquid hydrocarbons, such as liquid propane; liquid butane, gasoline distillates, kerosenes, etc., often referred to as parafllnic solvents, through an extraction zone, while introducing at an intermediate pointthereof the hydrocarbon mixture to be extracted. Upon being brought into contact with the two counterflowing solvents under suitable extracting conditions of temperature and pressure, the oil together with the solvents forms two liquid phases which separate within the extraction zone and are withdrawn therefrom. The withdrawn phases may then be treated to separate their oil portions from both orone of the solvents, or they may be subjected again tosolvent extraction.

It is to be understood that by identifying the solvents of this invention by chemical names, it is intended to include not only the chemically pure substances, but also the products of commerce which may contain various impurities, as well as various solutions and mixtures containing effective quantities of these substances and suitable for treating hydrocarbon oils by solvent extraction. Among such products may be listed the nitrogen bases obtained from coal tar and petroleum products by various processes such, for example, as extraction with mineral acids, since these bases contain considerable amounts of the heterocyclic compounds with a nitrogen atom in their ring. These nitrogen bases may be used for the purposes of this invention in such form as they are obtained in commercial process, or they may be subjected to a preliminary purification to increase the percentage of the heterocyclic compounds contained therein. It is understood that they may be used, according to this invention, in combination with any other solvents, such as furfural, nitro-benzene, chlorex, etc., and that the extraction with nitrogen bases may precede or follow the extraction withthese conventional solvents. It should be particularly noted that the nitrogen bases containing heterocyclic compounds with a nitrogen atom in their ring were found to be especially effective in removing asphaltic components of mineral oils without causing considerable losses of non-asphaltic materials.

- It is also understood that thenitrogen ring compounds, or the commercial products containing effective quantities of these compounds can beadvantageously used in dewaxing mineral oils. The oil to be dewaxed, such, for example, as the raflinate phase obtained in an extraction process,

may be saturated, either in the presence or in the absence of a dewaxing diluent, such as light naphtha, liquid propane, benzol, etc., with one of the nitrogen ring compounds forming the subject of this invention, the mixture being subsequentiychilled and the wax separated inconventional manner.

I claim as my invention:

1. In the processof treating a hydrocarbon oil containing asphaltic components, the steps of removing these asphaltic components by bringing the oil in contact with aquantity of a' solvent comprising a carbon substituted derivative of a nitrogen ring compound containing as substltuentsat least one of the following radiclesr CN, N02, 00, OR, COOR, Cl, and O, and where R designates a member of the group: hydrogen atom and alkyl radicles, said quantities being just sufficient to remove the asphaltic components without affecting the other components of the oil, separating the oil-solvent mixture into railinate and extract phases, and subjecting the oil component of the railinate phase to a second extraction with a naphthenic solvent to increase the concentration of the parafllnic components of the oil.

2. In the process of treating a hydrocarbon oil, the steps of extracting the oil with a naphthenic solvent to produce a rafiinate of a higher parafllnic content than the original oil but containing oilcoloring substances, and then extracting said coloring substances from the rafiinate with a solvent comprising a carbon substituted derivative of a nitrogen ring compound containing as substituents at least one of the following radicles: CN, N02, C0, OR, COOR, Cl, and O, and where R designates a member of the group: hydrogen atom and alkyl radicles.

3. A process for extracting a hydrocarbon oil to separate it into portions of different compositions, comprising the step of bringing said oil in contact with an effective quantity of a carbon substituted derivative of a nitrogen ring compound containing .as a substituent at least one of the following radicles: CN, N02, C0, OR, COOR, Cl and 0, where R designates a member of the group: hydrogen atom and alkyl radicles. thereby forming two liquid phases.

4. A process for extractinga hydrocarbon oil to separate it into portions of diilerent compositions, comprising the step of bringing said oil in to separate it into portions of,difierent compositions, comprising the step of bringing said oil in contact with an effective quantity ofa carbon substituted nitrogen ring compound containing as substituent at least one N0: radical, thereby forming two liquid phases.

WILLEM J. D. VAN DIJCK. 

